Turbine wheel



y 1, 1963 R. H. ASPlNWALL 3,090,597

TURBINE WHEEL Filed Oct. 20, 1962 I NVENTOR.

AT TORNE Y rates My invention relates to bladed wheels or disks such as those of turbine rotors. It involves a novel type of structure particularly desirable to facilitate casting the wheel and blades and to minimize stress in the parts during op eration which would otherwise result from thermal gradients. Casting of the blades integral with a turbine wheel is a promising method of fabrication, particularly for very small turbines. The difi'iculty of casting may be greatly reduced by casting the wheel in several sectors. My invention is directed to a wheel or disk made up of a number of sectors which together form a complete disk and which preferably have blades cast integral with them.

The nature of the invention and the advantages thereof will be apparent from the succeeding description of the preferred embodiment of the invention and the accompanying drawing thereof.

FIGURE 1 is a view of a turbomachine rotor element perpendicular to the axis thereof.

FIGURE 2 is a partial sectional view containing the axis taken on the plane indicated by the line 22 in FIGURE 1.

FIGURE 3 is a detail sectional View taken on the plane indicated by the line 3--3 in FIGURE 1.

The drawing shows a turbine wheel or disk D made up of four sectors S, each sector carrying a number of blades 13 extending from its outer edge. The four sectors S are assembled upon a shaft 6 which has a flat, keyway, or spline 7 so that the sectors are non-rotatably coupled to the shaft. Each of the sectors S comprises a hub 9 which encircles and fits closely onto the shaft. It includes one or if desired, more spokes 11 extending from the hub and a rim segment 12 extending in a generally T configuration from the spoke 11 and tapering circumferentially. The periphery of the rim portion is quadrantal, as shown, and all of the rim portions are aligned axially of the shaft 6. The hub portions 9 are otfset from the spoke 11 so that the four hubs of a single disk are in abutting relation on the shaft as shown in FTGURE 2. While four sectors are illustrated, this number may be varied.

Each sector also includes webs 14 and 15 which complete the outline of the disk and provide a structure to contain the gas and prevent the motive fluid from bypassing the blades. The webs 14 also provide a measure of support for the rim sector against centrifugal force. The web portions 15 are thickened at the radial edge and provided with a machined slot 17 which receives the web 14 of the adjacent sector. A tongue-and-groove connection with circumferential clearance is thus provided. A small gap is left at 19 between the ends of adjacent rim sectors 12. This prevents development of stresses in the disk because of diiferential heating or cooling of the rim and the body of the disk. The slip fit of the webs 14 in the slots 17 also permits local expansion without the development of harmful stresses.

The individual sectors S are cast and are machined 3,9ii,597 Fatentecl May 21, 1963 to the extent necessary to provide the hole 21 in the hub and to assure proper fit at the overlapping margins of the webs. By employing precision casting, it may be possible to dispense with all machining except that of hole 21. The invention aids the casting process, since relatively small pieces are required which may be cast more easily and with less scrap from poor castings than if the wheel is cast as a whole. The structure according to the invention is easily assembled and provides a bladed turbine disk which has maximum accommodation to temperature differences and thus a minimum of stress, fur ther adapting the structure to manufacture by casting.

The diiferentiation between the thicker spoke 11 and the thinner Web 14, 15 is not essential, since the sector might have a web of constant thickness throughout its angular extent around the axis, or a web gradually varying in thickness circumferentially.

Any suitable means including tack-welding or radial pins may be used to fix the hubs 9 against shifting along the shafit. Their relative angular position is determined by the keyway 7 so that the configuration of the wheel is stable, and it will remain in balance once the balancing has been accomplished.

The detailed description of the preferred embodiment of the invention is not to be construed as limiting the invention, since many modifications may be made by the exercise of skill in the art.

I claim:

1. A turbomachine rotor element comprising, in combination, a shaft, a disk on the shaft, and blades on the disk, the disk comprising a plural number of disk sectors together constituting a full disk; each sector having a hub in relatively non-rotatable engagement with the shaft, 3. web extending radially from the hub, a rim sector at the perimeter of the web, and blades extending from the rim sector; the several hubs being juxtaposed on the shaft, the webs being in overlapping contact relation to block leakage through the disk, and the rim sectors being slightly spaced from each other.

2. A rotor element as recited in claim 1 in which the blades and disk sectors are cast integrally together.

3. A turbomachine rotor element comprising, in combination, a shaft, a disk on the shaft, and blades on the disk, the disk comprising a plural number of disk sectors together constituting a full disk; each sector having a hub in relatively non-rotatable engagement with the shaft, a rim sector at the perimeter of the disk sector, a spoke extending radially from the hub and flaring around the rim sector, and a web completing the outline of the disk sector, and blades extending from the rim sector; the several hubs being juxtaposed on the shaft, the webs being in overlapping contact relation to block leakage through the disk, and the ends of the rim sectors being slightly spaced from each other.

4. A rotor element as recited in claim 3 in which the blades and disk sectors are cast integrally together.

References Cited in the file of this patent UNITED STATES PATENTS 672,315 Doble Apr. 16, 1901 1,260,562 McIntosh Mar. 26, 1918 2,748,045 Kelly May 29, 1956 2.906.349 Hans et al Sept. 29, 1959 

1. A TURBOMACHINE ROTOR ELEMENT COMPRISING, IN COMBINATION, A SHAFT, A DISK ON THE SHAFT, AND BLADES ON THE DISK, THE DISK COMPRISING A PLURAL NUMBER OF DISK SECTORS TOGETHER CONSTITUTING A FULL DISK; EACH SECTOR HAVING A HUB IN RELTIVELY NON-ROTATABLE ENGAGEMENT WITH THE SHAFT, A WEB EXTENDING RADIALLY FROM THE HUB, A RIM SECTOR AT THE PERIMETER OF THE WEB, AND BLADES EXTENDING FROM THE RIM SECTOR; THE SEVERAL HUBS BEING JUXTAPOSED ON THE SHAFT, THE WEBS BEING IN OVERLAPPING CONTACT RELATION TO BLOCK LEAKAGE THROUGH THE DISK, AND THE RIM SECTORS BEING SLIGHTLY SPACED FROM EACH OTHER. 